Recently, various technologies related to a wireless local area network (LAN) have become widespread. For example, as a wireless LAN technology, a protocol referred to as a block acknowledgement (hereinafter also referred as “block ACK”) for sequentially transmitting a plurality of pieces of data from a transmission-side communication device and then collectively returning reception confirmation from a reception-side communication device is used. For example, a method of performing an acknowledgement associated with the most recently transmitted transmission sequence indicator during block acknowledgement is disclosed (for example, refer to Patent Literature 1).